Scientists contrast the ways bird flu and human flu spread. They also
discuss how the flu responsible for the 1918 flu pandemic may have started as a
bird flu that changed to a form that could infect people and spread easily from
person to person.

This NOVA scienceNOW segment:

describes how the current bird flu infects people but does not spread
easily from person to person.

explains that the virus responsible for bird flu spreads through bird
feces, and the one that causes human flu spreads through coughing and
sneezing.

tells that the 1918 bird flu acquired characteristics that enabled it
not only to infect humans, but also to be efficiently transmitted by them to
other people.

uses a model to explain how viral-RNA copying mistakes might give rise
to a bird virus that can infect humans.

says that scientists do not know whether it is a large or small change
in a virus that allows it to spread from person to person.

reports that scientists do not yet know how dangerous the present bird
flu will be.

Taping Rights: Can be used up to one year after the program is taped off the air.